Iskanje po katalogu digitalne knjižnice

Opis: This study investigates the optimization of the design of timber floor joists, taking into account the self-manufacturing costs and the discrete sizes of the structure. This non-linear and discrete class of optimization problem was solved with the multi-parametric mixed-integer non-linear programming (MINLP). An MINLP optimization model was developed. In the model, an accurate objective function of the material and labor costs of the structure was subjected to design, strength, vibration and deflection (in)equality constraints, defined according to Eurocode regulations. The optimal design of timber floor joists was investigated for different floor systems, different materials (sawn wood and glulam), different load sharing systems, different vertical imposed loads, different spans, and different alternatives of discrete cross-sections. For the above parameters, 380 individual MINLP optimizations were performed. Based on the results obtained, a recommended optimal design for timber floor joists was developed. Engineers can select from the recommendations the optimal design system for a given imposed load and span of the structure. Economically suitable spans for timber floor joists structures were found. The current knowledge of competitive spans for timber floor joists is extended based on cost optimization and Eurocode standards.
Ključne besede: structural optimization, cost optimization, discrete optimization, mixed-integer nonlinear programming, MINLP, timber floor joists
Objavljeno v DKUM: 12.03.2025; Ogledov: 0; Prenosov: 0
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Opis: Optimizing open-end piles is crucial for sustainability as it minimizes material consumption and reduces environmental impact. By improving construction efficiency, less steel is needed, reducing the carbon footprint associated with production and transportation. Improved pile performance also results in more durable structures that require less frequent replacement and maintenance, which in turn saves resources and energy. This paper presents a parametric study on optimal designs for open-ended piles in sand, presenting a novel approach to directly compute optimal pile designs using CPT results. It addresses challenges posed by soil variability and layered conditions, with the optimization model accounting for interdependencies among pile length, diameter, wall thickness and soil properties, including the pile–soil plug system. A mixed-integer optimization model OPEN-Pile was developed, consisting of an objective function for pile mass and CO2 emissions. The objective function was constrained by a set of design and geotechnical conditions that corresponded to current codes of practice and recommendations. The efficiency of the developed optimization model is illustrated by two case studies. In the case of Blessington sand, the calculation results show that it is more economical and environmentally friendly to increase the pile diameter and pile wall thickness than the pile length. In efficient design, the ratio between diameter and wall thickness is calculated at the upper limit. For the optimum design of piles in Blessington sand, the optimum ratios of pile length to diameter, diameter to wall thickness and length to wall thickness are 5, 50 and 250, respectively. In a layered soil profile, the decision of where to place the pile base depends on the resistance of the cone tip and the thickness of the individual layers. To determine in which layer the pile base should be placed, we need to perform an optimization for the given design data.
Ključne besede: open-ended pile, computational modeling, structural optimization
Objavljeno v DKUM: 03.09.2024; Ogledov: 49; Prenosov: 14
Celotno besedilo (3,45 MB)
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Opis: The primary benefit of fuzzy systems theory is to approximate system behavior where analytic functions or numerical relations do not exist. In this paper, heuristic fuzzy rules were used with the intention of improving the performance of optimization models, introducing experiential rules acquired from experts and utilizing recommendations. The aim of this paper was to define soft constraints using an adaptive network-based fuzzy inference system (ANFIS). This newly-developed soft constraint was applied to discrete optimization for obtaining optimal solutions. Even though the computational model is based on advanced computational technologies including fuzzy logic, neural networks and discrete optimization, it can be used to solve real-world problems of great interest for design engineers. The proposed computational model was used to find the minimum weight solutions for simply-supported laterally-restrained beams.
Ključne besede: uncertainty, discrete optimization, neuro-fuzzy technique, structural optimization
Objavljeno v DKUM: 09.08.2017; Ogledov: 1474; Prenosov: 380
Celotno besedilo (1,10 MB)
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Opis: The paper describes the simultaneous topology, material, standard and rounded dimension optimization of mechanical structures, performed by the Mixed-Integer Non-linear Programming (MINLP) approach. Beside the generation of an MINLP mechanical superstructure, the development of a general multilevel MINLP formulation for a mechanical superstructure is presented. The consideration of the discrete materials as well as standard and particularly rounded dimensions in structural synthesis significantly increases the combinatorics of the discrete optimization, which as a result may become too difficult to solve. A Linked Multilevel Hierarchical Strategy (LMHS) has been introduced for the solving of such large combinatorial problems. In order to decrease the effect of non-convexities, the Modified Outer-Approximation/Equality-Relaxation (OA/ER) algorithm has been applied. Four numerical examples of different complexities are presented to illustrate the proposed multilevel MINLP optimization approach: the optimization of two steel trusses, a composite I beam and a hydraulic steel roller gate Intake gate, erected in Aswan II, Egypt.
Ključne besede: structural optimization, structural synthesis, MINLP, topology opitmization, material optimization, discrete variable optimization, multilevel MINLP strategy, truss, composite beam, roller gate
Objavljeno v DKUM: 01.06.2012; Ogledov: 2803; Prenosov: 109
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